Muffler with external tuning tube connecting internal chamber to exhaust conduit

ABSTRACT

There is an external tube which connects the exhaust pipe to a chamber of the muffler to provide a means for introducing a long tuning neck into the silencing structure thereby making it possible to attenuate low frequency notes with a minimum size muffler structure.

United States Patent [72] Inventor Bert Dubois Brookyn, Mich.

[211 Appl. No. 670,576

[22] Filed Sept. 26, 1967 [45] Patented June 8,1971

[73] Assignee Tenneco Inc.

Houston, Tex.

[54] MUFFLER WITH EXTERNAL TUNING TUBE CONNECTING INTERNAL CHAMBER T0 EXHAUST CONDUIT 4 Claims, 2 Drawing Figs.

[52] US. Cl 181/54,

[51] Int.C1 FOIn l/02,

F01n 1/08 [50] Field ofSearch 181/36.3, 4345, 48,51, 54, 59

[56] References Cited UNITED STATES PATENTS 1,331,275 2/1920 Miles 181/44 2,065,232 12/1936 MacKenzie et al. 181/48 2,297,046 9/1942 Bourne 181/48 2,468,454 4/1949 Mason 18 l/48X 3,090,677 5/1963 Scheitlin et a1. 181/45X 3,107,748 10/1963 Placek 181/54X 3,114,432 12/1963 Ludlow et a1 181/59 3,220,805 11/1965 Fowler et al. 181/45X 2,127,672 8/1938 Borune 181/59 3,209,858 10/1965 Jettinghoff 181/54 3,263,772 8/1966 Irwin et al...... 181/59 3,447,629 6/1969 Placek 181/54 FOREIGN PATENTS 221,069 3/1959 Australia 181/56 Primary Examiner Robert S. Ward, Jr. Attorney-Harness, Dickey & Pierce ABSTRACT: There is an external tube which connects the exhaust pipe to a chamber of the muffler to provide a means for introducing a long tuning neck into the silencing structure thereby making it possible to attenuate low frequency notes with a minimum size muffler structure.

BRIEF SUMMARY OF THE INVENTION In silencing the exhaust gases of an automotive engine the greatest practical difficulty is experienced with the low frequency notes since they require a large volume or a long tuning neck either of which means a large, expensive and hard to locate muffler structure.

It is the purpose of this invention to utilize the space outside of the muffler in the silencing of these low notes thereby minimizing the required size of the muffler. The invention accomplishes this by means of a relatively long tuning tube located outside of the muffler to acoustically connect a chamber inside the muffler to either the exhaust pipe or the tailpipe at a point remote from the inlet or outlet respectively of the muffler. The length and size of the external tuning tube and the volume of the chamber that it is connected to are interrelated in accordance with the Helmholtz formula so that the system is tuned to silence the desired low frequency.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective and somewhat schematic view of an exhaust system embodying the invention; and

FIG. 2 is an enlarged view including a cross section of the external tuning tube and muffler combination of this invention.

DESCRIPTION OF THE INVENTION FIG. 1 illustrates an exhaust system 1 that may be used as a dual system such asis popular for high performance in V8 automotive engines. The system includes left and right sides 3 and 5 respectively, each of which has an exhaust pipe 7 or 9 that is connected at its inlet end 11 or 13 to the exhaust manifolds (not shown) of the engine. The exhaust pipes 7 and 9 may be connected by a cross-branch 15 if desired. The exhaust pipes 7 and 9 empty into mufflers 17 and 19, which for the purpose of this invention may be regarded as identical, though this is not essential. The mufflers l7 and 19 empty respectively into tailpipes 21 and 23 which convey the gas to the rear of the vehicle and convey it to atmosphere.

Referring to FIG. 2 which is an exploded view of the pipes and muffler, the gas from the exhaust pipe 7 flows into inlet tube 25 inside of the shell 27 of the muffler 17. The shell 27 is preferably oval in cross section and its inlet end is closed by a header 29 and its outlet end by a header 31, the tube 25 being supported in the neck 33 of the header 29. There are four parallel transverse partitions 33, 35, 37 and 39 inside of the shell 27 which divide it into longitudinally adjacent chambers 41, 43, 45, 47 and 49. lnlet tube 25 passes through the chambers 41, 43, and 45 and empties into the chamber 47. The tube 25 is imperforate in the chambers 41 and 43, but may be provided with louvers 51 opening into the chamber 45. Gas in the chamber 47 reverses direction and flows through an intermediate tube 53, which may have louvers 55 opening in the chamber 45, to the chamber 43. Chamber 43 is connected by an outlet pipe 57, which extends through the various partitions and is supported in the neck 59 of outlet header 31, to the tailpipe 21. Louvers 61 in the outlet pipe 57 may be provided to open into the chamber 45. A tuning tube 63 connects the chamber 47 to the chamber 49 to provide a Helmholtz silencing system at that point.

In accordance with the invention, an external tuning tube 65 is welded at 67 around an opening (not shown) in the sidewall of the exhaust pipe 7 and is attached at its downstream end to a bushing 69 that is supported in a neck 71 on the inlet header 29 which opens into the closed chamber 41. It is apparent that no gas can flow through the chamber 41 so that the tube 65 acts as a long tuning neck for tuning the chamber 41 to the desired frequenc which it is desired to silence. In accordance with the He mholtz formula, as the length of the tuning tube 65 is increased the required volume of the chamber 41 to silence a given note is decreased. Thus, it will be seen that the arrangement described makes it possible to reduce the size of the muffler 17 and take advantage of space adjacent the exhaust pipe 7 which is otherwise unused.

The structure just described in connection with exhaust pipe 7, muffler l7 and tuning tube 65 may be used in connection with exhaust pipe 9 and muffler 19 by means of an external tuning tube 73 corresponding to tube 65. It is apparent that instead of or in addition to tuning tube opening into the exhaust pipe, one may be used in conjunction with the tailpipe 21 or 23 to connect a downstream point to a closed chamber inside of the muffler.

Modifications may be made in the structure shown without departing from the spirit and scope of the invention.

Iclaim:

1. In an exhaust gas system for an internal combustion engine including a pipe for conveying gas to or from the muffler, a muffler for silencing exhaust gases and including an outer shell and internal silencing and gas flow structure, said muffler having an inlet member and an outlet member one of which is connected to said pipe, said muffler including a closed chamber in said shell, and an external imperforate fully open tuning tube opening freely at one end into the said closed chamber and freely at the other end into said pipe at a point remote from said muffler and located outside of said shell, said tube being longer than said chamber and located alongside and outside of said pipe, the length and size of said external tuning tube and the volume of said closed chamber being interrelated in accordance with the Helmholtz formula and tuned to attenuate a desired frequency of sound.

2. An exhaust system for automotive vehicles, comprising an exhaust pipe, a tailpipe, and a muffler having an inlet connected to said exhaust pipe and an outlet connected to said tailpipe, said muffler having a plurality of sound attenuating chambers acoustically coupled to said inlet and outlet, at least one chamber in said muffler having an elongated throat connected directly to at least one of said exhaust and tailpipes, said throat and chamber being tuned to attenuate a desired frequency.

3. A muffler, comprising an outer shell, a pair of end caps mounted on said shell closing the ends thereof, inlet and outlet nipples, a pair of gas-carrying pipes connected to said nipples, means in said shell forming at least one sound attenuating chamber therein acoustically coupled to said inlet and outlet nipples, and a conduit mounted in one of said end caps and acoustically coupled to at least one chamber in said muffler, said conduit extending outwardly from said muffler for connection to one of said gas-carrying pipes, said conduit and the chamber to which it is coupled being tuned to attenuate a desired frequency.

4. In an exhaust gas system for an internal combustion engine including a pipe for conveying gas to or from the muffler, a muffler for silencing exhaust gases and including an outer shell and internal silencing and gas flow structure, said muffler having an inlet member and an outlet member one of which is connected to said pipe, said muffler including a closed chamber in said shell, and an external imperforate open tuning tube opening at one end into said closed chamber and at the other end into said pipe at a point remote from said muffler and located outside of said shell, the length and size of said external tuning tube and the volume of said closed chamber being interrelated in accordance with the Helmholtz formula and tuned to attenuate a desired frequency of sound. 

1. In an exhaust gas system for an internal combustion engine including a pipe for conveying gas to or from the muffler, a muffler for silencing exhaust gases and including an outer shell and internal silencing and gas flow structure, said muffler having an inlet member and an outlet member one of which is connected to said pipe, said muffler including a closed chamber in said shell, and an external imperforate fully open tuning tube opening freely at one end into the said closed chamber and freely at the other end into said pipe at a point remote from said muffler and located outside of said shell, said tube being longer than said chamber and located alongside and outside of said pipe, the length and size of said external tuning tube and the volume of said closed chamber being interrelated in accordance with the Helmholtz formula and tuned to attenuate a desired frequency of sound.
 2. An exhaust system for automotive vehicles, comprising an exhaust pipe, a tailpipe, and a muffler having an inlet connected to said exhaust pipe and an outlet connected to said tailpipe, said muffler having a plurality of sound attenuating chambers acoustically coupled to said inlet and outlet, at least one chamber in said muffler having an elongated throat connected directly to at least one of said exhaust and tailpipes, said throat and chamber being tuned to attenuate a desired frequency.
 3. A muffler, comprising an outer shell, a pair of end caps mounted on said shell closing the ends thereof, inlet and outlet nipples, a pair of gas-carrying pipes connected to said nipples, means in said shell forming at least one sound attenuating chamber therein acoustically coupled to said inlet and outlet nipples, and a conduit mounted in one of said end caps and acoustically coupled to at least one chamber in said muffler, said conduit extending outwardly from said muffler for connection to one of said gas-carrying pipes, said conduit and the chamber to which it is coupled being tuned to attenuate a desired frequency.
 4. In an exhaust gas system for an internal combustion engine including a pipe for conveying gas to or from the muffler, a muffler for silencing Exhaust gases and including an outer shell and internal silencing and gas flow structure, said muffler having an inlet member and an outlet member one of which is connected to said pipe, said muffler including a closed chamber in said shell, and an external imperforate open tuning tube opening at one end into said closed chamber and at the other end into said pipe at a point remote from said muffler and located outside of said shell, the length and size of said external tuning tube and the volume of said closed chamber being interrelated in accordance with the Helmholtz formula and tuned to attenuate a desired frequency of sound. 